Like many pathogens, the influenza virus deserves our (grudging) admiration. A collection of only 11 genes (for comparison, you have around 20 000) wrapped up in a protein shell, the virus is tiny - almost 1000 individual ‘flu viruses would fit end-to-end across a human hair. Despite its diminutive size, however, the virus can survive for up to 48 hours on surfaces, and a single aerosol droplet from an infected person can be sufficient to trigger a new infection. Once it gets inside the body, the virus invades epithelial cells lining the airway and starts to replicate. This process damages tissues, and triggers a very strong inflammatory response including most of the unwelcome symptoms of flu.
The influenza virus comes in three “flavours”: A, B, and C. Type A is typically the most serious in humans, and is the type largely responsible for winter flu outbreaks, such as the one we are experiencing now. Although there are many different influenza A viruses, only three types appear to infect humans: H1N1, H1N2 and H3N2.
Influenza A circulates naturally in bird populations in Asia but spreads effectively in cold conditions. The reasons for this are not fully understood, but probably include a complex mix of people spending more time indoors in crowded settings and environmental conditions that are more conducive to long-term survival of the virus. This can lead to it spreading to other regions of the globe during the southern and northern hemisphere winters. In fact, both “Aussie” and “French” flu are in reality, ’Asian’ flu.
The UK typically experiences a flu outbreak every winter, but is there anything special about this year’s infection? As far as we can tell at this stage, the virus itself is fairly unremarkable. Both Aussie and French ‘flu are Influenza-A, type H3N2, which is the same group that has been responsible for most winter flu cases in the UK in recent years. What is slightly unusual this year is the scale of the outbreak, and the number of patients who develop severe symptoms that require hospitalisation.
The current outbreak in France started in December, a month earlier than is typical for flu, and although the number of people affected is not higher than in previous years, the number requiring hospitalisation is about four times higher than would be expected. Whilst the French outbreak is predicted to be reaching its peak and should shortly start to decline, the UK outbreak started later and consequently the expectation is that cases will continue to rise for at least the next week or two.
Despite the fact that Aussie/ French flu is not likely to trigger a global apocalypse, most of us would still prefer not to experience it first-hand. Luckily, the current flu vaccine available, offers good (although not perfect) levels of protection, so getting the vaccine is a good idea, and is strongly recommended for those who are at particular risk such as the over-65s or pregnant women.
The key to avoiding flu is really stringent hygiene. Normal soap and water is a great way to kill a virus, so wash your hands regularly, try to minimise touching mouth and face and, if you develop coughs and sneezes, make sure you bin tissues immediately after use.
Lastly, one thing that won’t help with the flu is antibiotics. Influenza is a virus, not a bacterium, so antibiotics are completely ineffective and (mis)using them in this way risks accelerating the evolution of antibiotic resistance. However, it is important to note that some people who have had flu can develop a secondary and potentially dangerous bacterial pneumonia because of the lung damage the ‘flu virus causes. So if you had the flu, began to feel better but then start to feel worse again, it is recommended that you should visit your GP in case you need antibiotics to deal with a secondary bacterial infection.